Drive transmitter and image forming apparatus incorporating the drive transmitter

ABSTRACT

A drive transmitter includes an internally toothed gear, a first support shaft to rotatably support the internally toothed gear without using a bearing, a drive source to apply a driving force to the internally toothed gear, a rotary body to which the driving force is transmitted via the internally toothed gear, and a grease retainer disposed on the first support shaft and to retain grease on at least one of a portion of the first support shaft facing the internally toothed gear and a portion of the internally toothed gear facing the first support shaft. An image forming apparatus includes the drive transmitter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority pursuant to 35U.S.C. §119(a) to Japanese Patent Application No. 2014-128368, filed onJun. 23, 2014, in the Japan Patent Office, the entire disclosure ofwhich is hereby incorporated by reference herein.

BACKGROUND

1. Technical Field

This disclosure relates to a drive transmitter and an image formingapparatus that includes the drive transmitter.

2. Related Art

Drive devices are used for image formation performed in an image formingapparatus such as a copier, printer, facsimile machine, andmultifunction peripherals including at least two functions of thecopier, printer, and facsimile machine Specifically, drive devices areused to drive a photoconductor and a transfer belt.

An example of the drive device includes an internally toothed gear thatis a gear meshing with a motor gear of a drive motor. Such an internallytoothed gear can increase a contact ratio to restrict vibration of thegears and block noise by the internally toothed gear.

SUMMARY

At least one aspect of this disclosure provides a drive transmitterincluding an internally toothed gear, a first support shaft to rotatablysupport the internally toothed gear without using a bearing, a drivesource to apply a driving force to the internally toothed gear, a rotarybody to which the driving force is transmitted via the internal toothedgear, and a grease retainer disposed on the first support shaft and toretain grease on at least one of a portion of the first support shaftfacing the internally toothed gear and a portion of the internallytoothed gear facing the first support shaft.

Further, at least one aspect of this disclosure provides an imageforming apparatus including the drive transmitter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating a schematic configuration of an imageforming apparatus according to an example of this disclosure;

FIG. 2A is a perspective view illustrating a process cartridge includedin the image forming apparatus of FIG. 1;

FIG. 2B is a cross sectional view illustrating the process cartridge ofFIG. 2A;

FIG. 3 is a perspective view illustrating a drive device included in theimage forming apparatus of FIG. 1;

FIG. 4 is a perspective view illustrating an inside of the drive deviceof FIG. 3;

FIG. 5 is a cross sectional view illustrating the drive device of FIG.3;

FIG. 6 is a front view illustrating of the drive device on a motor side;

FIG. 7 is a perspective view illustrating the drive device where aphotoconductor drive gear and a photoconductor drive shaft are removedfrom a housing thereof;

FIGS. 8A and 8B are diagrams of a schematic configuration of areinforcement plate;

FIG. 9 is a perspective view illustrating the housing of the drivedevice where a resin molded product including the reinforcement plate, adeveloping idler gear, a development drive side coupling is furtherremoved from the housing of FIG. 7;

FIG. 10 is a diagram illustrating a slide portion where the resin moldedproduct having a developing internally toothed gear and a developingdriven gear slidably contacts a developing drive pin;

FIG. 11 is a perspective view illustrating the developing drive pinincluding a grease retainer;

FIG. 12 is an enlarged cross sectional view illustrating the developingdrive pin and peripheral parts of the drive device;

FIG. 13 is a diagram illustrating an action of the developing drive pin55 a in grease supply to the slide portion;

FIG. 14 is a diagram illustrating the developing drive pin according toanother example of this disclosure;

FIG. 15 is an enlarged cross sectional view illustrating the drivedevice having the developing drive pin according to an example of FIG.14;

FIG. 16 is a perspective view illustrating the developing drive pinaccording to yet another example of this disclosure;

FIG. 17A is a diagram illustrating a position of the grease retainer onthe developing drive pin of FIG. 16; and

FIG. 17B is an enlarged view illustrating a gear meshing of two gears ofFIG. 17A.

DETAILED DESCRIPTION

It will be understood that if an element or layer is referred to asbeing “on”, “against”, “connected to” or “coupled to” another element orlayer, then it can be directly on, against, connected or coupled to theother element or layer, or intervening elements or layers may bepresent. In contrast, if an element is referred to as being “directlyon”, “directly connected to” or “directly coupled to” another element orlayer, then there are no intervening elements or layers present. Likenumbers referred to like elements throughout. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items. Spatially relative terms, such as “beneath”,“below”, “lower”, “above”, “upper” and the like may be used herein forease of description to describe one element or feature's relationship toanother element(s) or feature(s) as illustrated in the figures. It willbe understood that the spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. For example, if thedevice in the figures is turned over, elements describes as “below” or“beneath” other elements or features would then be oriented “above” theother elements or features. Thus, term such as “below” can encompassboth an orientation of above and below. The device may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors herein interpreted accordingly.

Although the terms first, second, etc. may be used herein to describevarious elements, components, regions, layers and/or sections, it shouldbe understood that these elements, components, regions, layer and/orsections should not be limited by these terms. These terms are used todistinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present disclosure.

The terminology used herein is for describing particular embodiments andexamples and is not intended to be limiting of exemplary embodiments ofthis disclosure. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless the contextclearly indicates otherwise. It will be further understood that theterms “includes” and/or “including”, when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

Descriptions are given, with reference to the accompanying drawings, ofexamples, exemplary embodiments, modification of exemplary embodiments,etc., of an image forming apparatus according to exemplary embodimentsof this disclosure. Elements having the same functions and shapes aredenoted by the same reference numerals throughout the specification andredundant descriptions are omitted. Elements that do not demanddescriptions may be omitted from the drawings as a matter ofconvenience. Reference numerals of elements extracted from the patentpublications are in parentheses so as to be distinguished from those ofexemplary embodiments of this disclosure.

This disclosure is applicable to any image forming apparatus, and isimplemented in the most effective manner in an electrophotographic imageforming apparatus.

In describing preferred embodiments illustrated in the drawings,specific terminology is employed for the sake of clarity. However, thedisclosure of this disclosure is not intended to be limited to thespecific terminology so selected and it is to be understood that eachspecific element includes any and all technical equivalents that havethe same function, operate in a similar manner, and achieve a similarresult.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, preferredembodiments of this disclosure are described.

Now, a description is given of an image forming apparatus 100 accordingto an example of this disclosure with reference to FIGS. 1, 2A, and 2B.

FIG. 1 is a diagram illustrating a schematic configuration of the imageforming apparatus 100 according to an example of this disclosure. FIG.2A is a perspective view illustrating a process cartridge 1 included inthe image forming apparatus 100 of FIG. 1. FIG. 2B is a cross sectionalview illustrating the process cartridge 1 of FIG. 2A.

The image forming apparatus 100 includes an image reading device 200disposed on top of an apparatus body 120 of the image forming apparatus100.

The apparatus body 120 of the image forming apparatus 100 includes theprocess cartridge 1, as illustrated in FIG. 1.

As illustrated in FIG. 2B, the process cartridge 1 includes aphotoconductor 10, a charger 11, a developing device 12, and a cleaningdevice 14.

The photoconductor 10 functions as an image bearer. The charger 11, thedeveloping device 12, and the cleaning device 14 are disposed around thephotoconductor 10 to function as image processing units for forming animage on the photoconductor 10.

The process cartridge 1 is detachably attachable to the apparatus body120. Since the photoconductor 10, the charger 11, the developing device12, and the cleaning device 14 are provided together in the processcartridge 1 as a unit, replacement of the process cartridge 1 andmaintenance of the image forming apparatus 100 can be performed easily.In addition, respective positions of the units and components in theimage forming apparatus 100, and therefore quality of image formed inthe image forming apparatus 100 can be enhanced.

The charger 11 includes a charging roller 11 a and a removing roller 11b. The charging roller 11 a uniformly charges a surface of thephotoconductor 10. The removing roller 11 b removes foreign materialsuch as toner attached to the surface of the charging roller 11 a.

The developing device 12 includes a first powder chamber V1 and a secondpowder chamber V2. The first powder chamber V1 is provided with a firstconveying screw 12 b that functions as a developer conveyor. The secondpowder chamber V2 is provided with a second conveying screw 12 c thatfunctions as a developer conveyor, a developing roller 12 a thatfunctions as a developer bearer, and a doctor blade 12 d that functionsas a developer regulator.

Both the first powder chamber V1 and the second powder chamber V2contain developer, specifically, two-component developer that includesmagnetic carriers and negatively charged toner. The first conveyingscrew 12 b is rotated by a drive unit to convey the developer containedin the first powder chamber V1 toward a near side in FIG. 2B. Thedeveloper conveyed by the first conveying screw 12 b to an end of thenear side of the first powder chamber V1 in FIG. 2B enters in the secondpowder chamber V2.

The second conveying screw 12 c of the second powder chamber V2 isrotated by a drive unit to convey the developer entered into the secondpowder chamber V2 toward a far side in the FIG. 2B. Above the secondconveying screw 12 c that conveys the developer as described above, thedeveloping roller 12 a is disposed in a parallel position with respectto the second conveying screw 12 c. The developing roller 12 a includesa magnet roller fixed inside a developing sleeve that is a rotarynon-magnetic sleeve.

Part of the developer conveyed by the second conveying screw 12 c istaken up to a surface of the developing roller 12 a due to a magneticforce exerted by a magnet roller located inside the developing roller 12a. The doctor blade 12 d is disposed facing the developing roller 12 awith a given gap with the surface of the developing roller 12 a andregulates a thickness of layer of the developer attached onto thesurface of the developing roller 12 a.

After the doctor blade 12 d regulates the layer thickness of thedeveloper on the developing roller 12 a, the developer on the developingroller 12 a is conveyed to a developing region located at a positionfacing the photoconductor 10. In the developing region, toner of thedeveloper is attached to an electrostatic latent image formed on thesurface of the photoconductor 10. Thus, a toner image is formed on thephotoconductor 10.

After consuming the toner due to the above-described development of thetoner image, the developer is returned to the second conveying screw 12c along with movement of the surface of the developing roller 12 a. Thesecond conveying screw 12 c conveys the toner-consumed developer to theend of the second powder chamber V2, so that the developer goes back tothe first powder chamber V1. Accordingly, the developer circulates inthe developing device 12.

The developing device 12 includes a toner concentration sensor thatdetects concentration of toner in the developer contained in the firstpowder chamber V1. The toner concentration sensor measures theconcentration of toner in the developer based on magnetic permeabilityof the developer. As the concentration of toner decreases, theconcentration of magnetic carriers in the developer increases, andtherefore the magnetic permeability becomes higher.

When a value measured and obtained by the toner concentration sensorexceeds a target value, i.e., a threshold value, the toner is suppliedfrom the toner bottle 20 to control the toner concentration to aconstant value. The target value is determined based on a detectionresult obtained by an optical sensor that detects an amount ofattachment of toner to a toner pattern formed on the photoconductor 10.

With the above-described operations, a reference pattern density on thephotoconductor 10 is controlled to a constant value. However, when thetoner bottle 20 is out of toner, a reduction in toner concentrationcannot be prevented. In such a situation, even after the toner bottle 20performs toner supply for a given time period, the detection result ofthe toner pattern obtained by the optical sensor is not corrected.Therefore, in a case in which the detection result of the toner patternobtained by the optical sensor does not get better even after the tonerbottle 20 supplies toner, a determination unit or a controllerdetermines or estimates an end of toner in the toner bottle 20.

After the end of toner is determined by the determination unit or thecontroller, the toner bottle 20 is replaced to a new toner bottle 20. Inan end-of-toner recovery performance, fresh toner in the new tonerbottle 20 is supplied to the developing device 12 in the followingprocedures.

In order to mix the toner and the developer well, the developing roller12 a, the first conveying screw 12 b, and the second conveying screw 12c are rotated. At the same time, in order to prevent nonuniformity ofdeveloper sliding on the developing roller 12 a, the photoconductor 10is also driven to rotate.

The cleaning device 14 that functions as a cleaner includes a cleaningblade 14 a and a toner collecting coil 14 b. The cleaning blade 14 acontacts the surface of the photoconductor 10 and scrapes residual tonerremaining on the surface of the photoconductor 10. The toner collectingcoil 14 b is contained in a collecting part W to convey collected tonerthat is collected by the cleaning blade 14 a. The collected tonerconveyed by the toner collecting coil 14 b is conveyed by a tonerconveying device to either the developing device 12 or a waste tonerbottle 41.

The image forming apparatus 100 further includes a transfer device 17 athermal fixing device 24, a laser writing device 21, and multiple sheettrays 22 in the apparatus body 120, as illustrated in FIG. 1.

The transfer device 17 includes a transfer roller 16 that is pressedagainst the surface of the photoconductor 10.

The thermal fixing device 24 that functions as a fixing device isdisposed above the transfer device 17. The thermal fixing device 24includes a heat roller 25 and a pressure roller 26.

The laser writing device 21 that functions as a latent image formingdevice includes a laser light source, a polygon mirror for scanning, apolygon motor, and a f-theta (ID) lens.

Each of the multiple sheet trays 22 disposed vertically in stepsaccommodates a sheet S such as a transfer sheet and an overheadprojector (OHP) sheet.

To generate a copy using the above-described image forming apparatus100, a user or an operator presses a start switch provided on the imageforming apparatus 100. As the start switch is pressed, the image readingdevice 200 of the image forming apparatus 100 scans image data of anoriginal document placed thereon. At the same time, a photoconductordrive motor provided to the image forming apparatus 100 rotates thephotoconductor 10, so that the charger 11 including the charging roller11 a uniformly charges the surface of the photoconductor 10. Then, thelaser writing device 21 emits laser light based on the image datascanned by the image reading device 200 to irradiate the surface of thephotoconductor 10 for forming an electrostatic latent image. Thereafter,the developing device 12 supplies toner to the electrostatic latentimage, so as to develop the electrostatic latent image with the tonerattached into a visible toner image.

At the same time the user presses the start switch, a pickup roller 27picks up and feeds the sheet S from a selected one of the multiple sheettrays 22. A sheet feed roller 28 and a sheet separation roller 29separate the sheet S one by one and convey the separated sheet S to asheet feed path R1.

The sheet S fed to the sheet feed path R1 is conveyed by a sheetconveying roller 30. While traveling in the sheet feed path R1, thesheet S abuts against a registration roller pair 23 to stop. Insynchronization with movement of the toner image formed on the surfaceof the photoconductor 10, the sheet S is conveyed to a transfer nipregion that is formed between the transfer roller 16 and thephotoconductor 10 in contact with each other.

The sheet S conveyed to the transfer nip region receives the toner imagefrom the photoconductor 10 by the transfer device 17.

After transfer of the toner image to the sheet S, residual toner andresidual electric potential remain on the surface of the photoconductor10. The residual toner is removed by the cleaning device 14 and theresidual electric potential is removed by an electric dischargingdevice. Thus, the photoconductor 10 becomes ready for a subsequent imageforming operation that starts from electric charges by the charger 11.

By contrast, the sheet S having the toner image thereon is conveyed tothe thermal fixing device 24. In the thermal fixing device 24, the sheetS passes between the heat roller 25 and the pressure roller 26 to fixthe toner image to the sheet S by application of heat and pressure whilebeing conveyed by the heat roller 25 and the pressure roller 26. Afterthe toner image is fixed to the sheet S, a sheet discharging roller pair31 conveys the sheet S to a discharged sheet stacker 32 to be stackedthereon.

Next, a description is given of details of the image forming apparatus100 according to an example of this disclosure with reference to FIGS.3, 4, and 5.

FIG. 3 is a perspective view illustrating a drive device 50 included, inthe image forming apparatus 100 of FIG. 1. FIG. 4 is a perspective viewillustrating an inside of the drive device 50 of FIG. 3. FIG. 5 is across sectional view illustrating a schematic configuration of the drivedevice 50 of FIG. 3.

The drive device 50 drives the photoconductor 10 and the developingroller 12 a. The drive device 50 includes a holder 60 to retain drivetransmitting members such as a photoconductor drive motor 51, adeveloping motor 52, and gears to transmit respective driving forces ofthe photoconductor drive motor 51 and the developing motor 52, both ofwhich functioning as a drive source.

The holder 60 includes a resin housing 61, a bracket 62, and a vibrationcontrol panel 63. The bracket 62 is a metallic bracket that functions asa first holding member. The vibration control panel 63 is a metallicpanel that functions as a second holding member. As illustrated in FIGS.4 and 5, the resin housing 61 accommodates a photoconductor drive gear53, a developing internally toothed gear 55, a developing driven gear56, and a developing idler gear 57, each of which functioning as a drivetransmitting member. The resin housing 61 further accommodates drivetransmitting members that transmit a driving force to a waste tonerconveying screw by which waste toner collected and fallen into the wastetoner bottle 41 is conveyed to a far side of the waste toner bottle 41.Specifically, these drive transmitting members are a conveyance drivegear 71, a conveyance drive pulley 72, a conveyance timing belt 73, aconveyance driven pulley 74, and a conveyance idler gear 75.

The photoconductor drive gear 53 is fixed to a photoconductor driveshaft 53 a that is formed by metal and is rotatably supported by theholder 60 and is meshed with a motor gear 51 a of the photoconductordrive motor 51. One end of the photoconductor drive shaft 53 a passesthrough the bracket 62 and the vibration control panel 63 and isrotatably supported to the bracket 62. The other end of thephotoconductor drive shaft 53 a is attached by a photoconductor driveside coupling 54 and is rotatably supported to the resin housing 61. Thephotoconductor drive side coupling 54 is linked to a photoconductordriven side coupling that is fixed to one end of a rotary shaft of thephotoconductor 10.

The developing internally toothed gear 55 is rotatably supported by adeveloping drive pin 55 a and is meshed with a motor gear 52 a of thedeveloping motor 52. The motor gear 52 a functions as an externallytoothed gear. The developing drive pin 55 a that functions as a supportshaft is formed by metal and is fixed to the resin housing 61. Thedeveloping internally toothed gear 55 and the developing driven gear 56that is disposed coaxially with the developing internally toothed gear55 are made as a resin integrated molding. The developing driven gear 56is meshed with the developing idler gear 57. A tip of the developingdrive pin 55 a is fitted and positioned to the bracket 62.

A developing drive side coupling 58 is mounted on an axial center of thedeveloping idler gear 57. The developing drive side coupling 58 passesthrough the resin housing 61 and is rotatably supported by the resinhousing 61. The developing drive side coupling 58 is linked to adeveloping driven side coupling that is fixed to an end of a rotaryshaft of the developing roller 12 a. The developing idler gear 57 andthe developing drive side coupling 58 are made as a resin integratedmolding.

Further, the motor gear 51 a of the photoconductor drive motor 51 ismeshed with the conveyance drive gear 71. The conveyance drive pulley 72is made with the conveyance drive gear 71 as a resin integrated moldingand the conveyance driven pulley 74 is made with the conveyance idlergear 75 as a resin integrated molding. The conveyance timing belt 73 iswound around the conveyance drive pulley 72 and the conveyance drivenpulley 74.

Instead of the conveyance timing belt 73, a conveyance V-belt may beemployed to transmit a driving force via respective frictional forces ofthe conveyance drive pulley 72 and the conveyance driven pulley 74.

One end of the resin integrated molding that includes the conveyancedrive gear 71 and the conveyance drive pulley 72 is rotatably supportedby a conveyance drive pin 72 a that is formed by metal and is fixed tothe resin housing 61. A tip of the conveyance drive pin 72 a is fittedand positioned to the bracket 62.

The resin integrated molding that includes the conveyance idler gear 75and the conveyance driven pulley 74 is rotatably supported by aconveyance driven pin 74 a that is formed by metal and is fixed to theresin housing 61. A tip of the conveyance driven pin 74 a is fitted andpositioned to the bracket 62.

As illustrated in FIG. 4, part of the conveyance idler gear 75 isexposed from a side opening 61 a of the resin housing 61. A screw drivegear 76 is fixed to one end of a screw shaft 77 a of the waste tonerconveying screw. As illustrated in FIG. 5, the screw drive gear 76 ismeshed with the conveying idler gear 75 through the side opening 61 a.

As illustrated in FIG. 3, one end of a ground plate 65 that is groundedis screwed to the bracket 62 with a screw 83. Further, one end of thephotoconductor drive shaft 53 a that is passed through the bracket 62 isfixed to one end of a grounding electrode 64. The other end of thegrounding electrode 64 is screwed to the bracket 62 with a screw 82.Accordingly, the photoconductor 10 is grounded via the photoconductordrive shaft 53 a, the grounding electrode 64, the bracket 62, and theground plate 65.

A description is given of a detailed configuration of the drive device50 according to an example of this disclosure, with reference to FIGS. 6through 13.

FIG. 6 is a front view illustrating of the drive device 50 on a motorside. As illustrated in FIG. 6, the vibration control panel 63 and thebracket 62 are disposed overlapping each other. Five (5) end portions ofthe vibration control panel 63 are fixed to the resin housing 61 byrespective screws 81 a through 81 e via the bracket 62. Consequently,the bracket 62 and the vibration control panel 63 are partly bonded toeach other with the screws 81 a through 81 e at the five end portions ofthe vibration control panel 63. In addition, the photoconductor drivemotor 51 and the developing motor 52 are screwed to the bracket 62 viathe vibration control panel 63.

The holder 60 of the drive device 50 includes multiple vibrationmembers, for example, multiple drive transmitting members such as thephotoconductor drive gear 53 and the developing internally toothed gear55, the photoconductor drive motor 51, and the developing motor 52. Itis likely that vibration caused by the multiple vibration membersgenerates noise. Vibration caused by the photoconductor drive motor 51and the developing motor 52 is transmitted to the vibration controlpanel 63 that contacts the photoconductor drive motor 51 and thedeveloping motor 52, and therefore the vibration control panel 63vibrates. By contrast, vibration caused by the multiple drivetransmitting members such as the photoconductor drive gear 53 and thedeveloping internally toothed gear 55 is transmitted to the bracket 62via the photoconductor drive shaft 53 a, the developing drive pin 55 a,the conveyance drive pin 72 a, and the conveyance driven pin 74 a. As aresult, this transmission of vibration vibrates the bracket 62.

As previously described, the bracket 62 and the vibration control panel63 are disposed overlapping each other and partly bonded to each otherwith the screws 81 a through 81 e at the five end portions of thevibration control panel 63, as illustrated in FIG. 6. Therefore, thevibration control panel 63 and the bracket 62 do not vibrate togetherbut vibrate individually. Specifically, the vibration control panel 63vibrates due to vibration caused by the photoconductor drive motor 51and the developing motor 52 and the bracket 62 vibrates due to vibrationcaused by the multiple transmission members such as gears contained inthe resin housing 61. The vibrations of the vibration control panel 63and the bracket 62 interfere with each other at the five end portionswhere the vibration control panel 63 and the bracket 62 are screwed withthe screws 81 a through 81 e at the five end portions of the vibrationcontrol panel 63. At this time, respective rigidities and bondingportions of the vibration control panel 63 and the bracket 62 areadjusted so as to generate a phase difference to cancel vibration of thevibration control panel 63 and vibration of the bracket 62 with eachother at the bonding portions. By so doing, respective amounts ofvibrations of the vibration control panel 63 and the bracket 62 arereduced.

FIG. 7 is a perspective view illustrating the drive device 50 where thephotoconductor drive gear 53 and the photoconductor drive shaft 53 a areremoved from the resin housing 61 thereof.

As illustrated in FIG. 7, a reinforcement plate 90 is screwed to theresin housing 61. The reinforcement plate 90 functions as a reinforcingmember to reinforce the resin housing 61.

FIGS. 8A and 8B are diagrams of a schematic configuration of thereinforcement plate 90.

As illustrated in FIGS. 8A and 8B, the reinforcement plate 90 includes adeveloping support shaft 91 that rotatably supports the resin integratedmolding including the developing idler gear 57 and the developing driveside coupling 58. The reinforcement plate 90 has screw through holes 90a, 90 b, and 90 c at three different portions, through which respectivescrews pass. The screw through holes 90 a, 90 b, and 90 c function asrespective fixing portions.

Further, the reinforcement plate 90 are further provided with a subreference hole 92 a and a main reference hole 92 b. The sub referencehole 92 a is a slot and the main reference hole 92 b is a round opening.As illustrated in FIG. 7, both the sub reference hole 92 a and the mainreference hole 92 b are fitted to respective positioning projections 611provided to the resin housing 61. By so doing, the reinforcement plate90 is positioned to the resin housing 61.

As illustrated in FIG. 8B, the developing support shaft 91 is providedin a position of the center of gravity of a polygon that is formed byconnecting fixed portions D1, D2, and D3 of the reinforcement plate 90to be fixed to the resin housing 61. The fixed portions D1, D2, and D3are respective centers of the screw through holes 90 a, 90 b, and 90 c,respectively. In this example, the polygon is a triangle.

By providing the developing support shaft 91 at the above-describedposition, a force applied to the developing support shaft 91 can bedispersed equally to three fixed portions of the reinforcement plate 90,and therefore torsion of the reinforcement plate 90 can be prevented.

FIG. 9 is a perspective view illustrating the resin housing 61 of thedrive device 50 where the resin integrated molding that includes thereinforcement plate 90, the developing idler gear 57, and the developingdrive side coupling 58 is further removed from the resin housing 61 ofFIG. 7.

As illustrated in FIG. 9, the resin housing 61 includes a first storagerecess 61 b that stores the photoconductor drive side coupling 54, asecond storage recess 61 c that stores the developing idler gear 57, anda third storage recess 61 d that stores the developing driven gear 56.The first storage recess 61 b, the second storage recess 61 c, and thethird storage recess 61 d are continuously connected to each other toform a large recess, and a substantially center of the resin housing 61is recessed significantly in a vertical direction of the resin housing61 in FIG. 9. The large recess of the resin housing 61 has a lowerrigidity, and therefore the resin housing 61 can be easily deformed inthe large recess when a compressive force is applied to the resinhousing 61 in a horizontal (left-to-right) direction in FIG. 9.Therefore, as illustrated in FIG. 7, in order to reinforce the resinhousing 61, the reinforcement plate 90 is fixed to the resin housing 61such that the reinforcement plate 90 is bridged across the large recessformed by three storage recesses (i.e., the first storage recess 61 b,the second storage recess 61 c, and the third storage recess 61 d)connected to each other. According to this configuration, thereinforcement plate 90 is extended stiff with respect to the compressiveforce applied in the horizontal direction in FIG. 9, and thereforedeformation of the resin housing 61 can be prevented. As a result, theabove-described configuration can prevent the resin housing 61 fromvibration, and therefore can reduce vibration of the drive device 50.

In this example, the developing internally toothed gear 55 is a gearthat meshes with the motor gear 52 a of the developing motor 52. By sodoing, a contact ratio with the motor gear 52 a can be increased, andoccurrence of rotation fluctuation, noise, and vibration can beprevented.

As a comparative example, there is a drive transmitter that includes aninternally toothed gear formed of resin and a support shaft fixed to aframe thereof. The internally toothed gear is rotatably supported by thesupport shaft directly without using a bearing.

Such resin internally toothed gears can reduce the weight, noise, andfriction compared with metallic gears.

The drive device 50 according to this example includes gears formed ofresin having high lubricity such as polyacetal (POM) having goodsmoothness. However, if the developing internally toothed gear 55 isformed of resin having high lubricity, sufficient strength thereofcannot be obtained. An internally toothed gear is provided with teeth ona cylindrical inner circumferential surface thereof, and therefore, dueto structure reasons, the rigidity thereof is lower than the rigidity ofan externally toothed gear that is provided with teeth on a cylindricalouter circumferential surface thereof. In addition, since the externallytoothed gear is inserted to the internally toothed gear, the internallytoothed gear cannot be reinforced by providing ribs therein.Accordingly, the rigidity of an internally toothed gear cannot beincreased, and therefore sufficient strength cannot be obtained.

For the above-described reasons, the configuration of this exampleemploys the high-rigidity resin integrated molding that includes thedeveloping internally toothed gear 55 and the developing driven gear 56.

However, there are tradeoffs between rigidity and lubricity of resin. Ina case (in a comparative example) in which the resin integrated moldinghaving the developing internally toothed gear 55 and the developingdriven gear 56 is formed by a resin having high rigidity, smoothnessthereof with the developing drive pin 55 a is reduced. As a result, itis likely that abnormal sound is generated between the developing drivepin 55 a and the resin integrated molding including the developinginternally toothed gear 55 and the developing driven gear 56. Further,it is also likely to cause inconvenience that the developing drive pin55 a provided in the resin integrated molding is worn at an early stage.

However, there are tradeoffs between rigidity and lubricity. Aninternally toothed gear formed with high-rigidity resin increases afriction force between a support shaft and the internally toothed gear,thereby decreasing smoothness. As a result, when the internally toothedgear slides on the support shaft, inconveniences such as abnormal soundand abrasion of the internally toothed gear and the support shaft havebeen generated.

Therefore, the internally toothed gear may be rotarably supported by asupport shaft via a bearing. However, the bearing is employed to thisconfiguration, and therefore the number of parts increases to cause anincrease in cost of the image forming apparatus.

Further, the internally toothed gear may be unrotatably fixed to thesupport shaft and the support shaft may be rotatably fixed to a frame ofthe drive device without the bearing. The frame of the drive devicesupports multiple parts such as a drive motor and drive transmittingunits, and therefore includes glass fiber, for example, to obtainrigidity greater than the internally toothed gear. Since the frame ofthe drive device has the rigidity greater than the internally toothedgear, the lubricity thereof is lower than the internally toothed gear,and therefore the smoothness between the frame and the support shaft islower than smoothness between the internally toothed gear having a highrigidity and the support shaft. Due to these reasons, it is notpreferable to employ a configuration in which the internally toothedgear is unrotatably fixed to the support shaft and the support shaft isrotatably fixed to the frame of the drive device without the bearing.Further, when the support shaft is rotatably supported to the frame ofthe drive device via the bearing, the bearing may need to thisconfiguration, and therefore an increase in the number of parts cancause an increase in cost of the image forming apparatus.

In this example, the developing drive pin 55 a includes a greaseretainer to retain or contain grease. The grease retainer suppliesgrease to a slide portion where the resin integrated molding thatincludes the developing internally toothed gear 55 and the developingdriven gear 56 contacts the developing drive pin 55 a.

A detailed description is given of the grease retainer included in thedeveloping drive pin 55 a.

FIG. 10 is a diagram illustrating a slide portion SP where a resinmolding 550 that includes the developing internally toothed gear 55 andthe developing driven gear 56 slidably contacts the developing drive pin55 a.

As illustrated in FIG. 10, the slide portion SP of the resin molding 550with respect to the developing drive pin 55 a is located at or in thevicinity of an end of a pin inserting hole 550 a to which the developingdrive pin 55 a of the resin molding 550 is inserted. The location of theslide portion SP is determined based on a fact that an end area of thepin inserting hole 550 a can be molded with accuracy while sink marksare generated in a center area of the pin inserting hole 550 a due to amold structure. Therefore, the center area of the pin inserting hole 550a is formed greater than a given inner diameter. As a result, the endarea of the pin inserting hole 550 a having a good mold structurecontacts and slides with the developing drive pin 55 a.

FIG. 11 is a perspective view illustrating the developing drive pin 55 aincluding a grease retainer. FIG. 12 is an enlarged cross sectional viewillustrating the developing drive pin 55 a and peripheral parts of thedrive device 50.

As illustrated in FIG. 11, a grease retaining groove 155 a thatfunctions as a ring or circular grease retainer is disposed adjacent tothe slide portion SP to slide into the pin inserting hole 550 a in anaxial direction on the developing drive pin 55 a. It is to be noted thatthe developing drive pin 55 a may include one or more slide portions SPand one or more grease retaining grooves 155 a. For example, thedeveloping drive pin 55 a illustrated in FIG. 11 includes two slideportions SP and two grease retaining grooves 155 a. The developing drivepin 55 a further includes a fitting member 155 b and a flange 155 c. Thefitting member 155 b fits in the resin housing 61. The flange 155 ccontacts a face of the resin housing 61 when the fitting member 155 b isfitted in the resin housing 61.

As illustrated in FIG. 12, the developing drive pin 55 a of this exampleincludes a grease retainer groove 155 a that functions as a greaterretainer. The grease retainer groove 155 a is a groove facing the innercircumferential surface of the pin inserting hole 550 a extending in acircumferential direction of the developing drive pin 55 a other thanthe slide portion SP where the developing drive pin 55 a slides on thepin inserting hole 550 a.

FIG. 13 is a diagram illustrating an action of the developing drive pin55 a in grease supply to the slide portion SP.

As illustrated in FIG. 13, a diameter of the pin inserting hole 550 agradually increases toward the center thereof due to sink marksgenerated in molding. Therefore, a gap between the developing drive pin55 a and the pin inserting hole 550 a tapers toward the slide portionSP. Consequently, according to capillary phenomenon, grease held in thegrease retaining groove 155 a flows toward the slide portion SP havingthe smaller gap, thereby supplying grease to the slide portion SP. Bysupplying grease in the grease retaining groove 155 a to the slideportion SP, the slide portion SP is lubricated, and therefore thefriction between the developing drive pin 55 a and the resin molding 550in the slide portion SP can be reduced. Accordingly, the above-describedconfiguration of this example can prevent occurrence of abnormal soundin the slide portion SP and abrasion on the slide portion SP of the pininserting hole 550 a.

Grease may be applied to the end of the pin inserting hole 550 a. Asillustrated in FIG. 12, the end of the pin inserting hole 550 a on theside of the developing roller 12 a is in contact with the flange 155 cof the developing drive pin 55 a, and therefore slides on the flange 155c when transmitting a driving force.

Further, the resin molding 550 may move to the side of the developingmotor 52. As illustrated in FIG. 12, the pin inserting hole 550 a islocated closer or projected to the developing motor 52 than an end N1 ofthe developing internally toothed gear 55 is. According to thisstructure, when the resin molding 550 moves to the side of thedeveloping motor 52, an end of the pin inserting hole 550 a on the sideof the developing motor 52 contacts the bracket 62, and therefore slideson the bracket 62 when transmitting the driving force. By applyinggrease to the end of the pin inserting hole 550 a, smoothness of the pininserting hole 550 a on the flange 155 c and the bracket 62 can beenhanced.

Now, a description is given of a developing drive pin 55 a 1 accordingto another example of this disclosure with reference to FIGS. 14 and 15.

FIG. 14 is a diagram illustrating a structure of the developing drivepin 55 a 1 according to another example of this disclosure. FIG. 15 isan enlarged cross sectional view illustrating the drive device 50 havingthe developing drive pin 55 a 1 of FIG. 14.

As illustrated in FIG. 14, the developing drive pin 55 a 1 of thisexample includes a grease retainer 155 a 1. The grease retainer 155 a 1is a groove facing the inner circumferential surface of the pininserting hole 550 a extending in a circumferential direction of thedeveloping drive pin 55 a 1 other than the slide portion SP where thedeveloping drive pin 55 a 1 slides on the pin inserting hole 550 a.

According to this structure, the grease retainer 155 a 1 can retain agreater amount of grease when compared to a structure in which thegrease retainer 155 a 1 is a cyclic groove disposed adjacent to theslide portion SP, and supply grease to the slide portion SP for a longtime. By so doing, the slide portion SP can be more smooth with greasefor a long time, and therefore occurrence of abnormal sound and abrasionof the slide portion SP where the developing drive pin 55 a 1 slides onthe pin inserting hole 550 a can be prevented for a long time.

Now, a description is given of a developing drive pin 55 a 2 accordingto yet another example of this disclosure with reference to FIGS. 16,17A, and 17B.

FIG. 16 is a perspective view illustrating the developing drive pin 55 a2 according to yet another example of this disclosure.

As illustrated in FIG. 16, the developing drive pin 55 a 2 includes agrease retainer 155 a 2 that is a groove that extends in an axialdirection of the developing drive pin 55 a 2.

In this example, when the developing drive pin 55 a 2 is formed ofresin, it is easiest and preferable to mold the developing drive pin 55a 2 by resin due to a mold structure.

FIG. 17A is a diagram illustrating a position of the grease retainer 155a 2 on the developing drive pin 55 a 2 of FIG. 16. FIG. 17B is a diagramillustrating an enlarged view of the gear meshing of the motor gear 52 aof the developing motor 52 and the developing internally toothed gear55.

As illustrated in FIGS. 17A and 17B, it is preferable that the greaseretainer 155 a 2 is located to the side of which the motor gear 52 a ofthe developing motor 52 and the developing internally toothed gear 55are meshed with each other. Specifically, it is preferable that thegrease retainer 155 a 2 is located on a line connecting an axial centerO1 of the developing drive pin 55 a 2 and a meshing portion K whereteeth of the motor gear 52 a mesh with teeth of developing internallytoothed gear 55. In other words, the grease retainer 155 a 2 is locatedon a side of the meshing portion K when viewed in the axial direction ofthe developing drive pin 55 a 2.

A pressure angle θ of which the teeth of the motor gear 52 a of thedeveloping motor 52 apply a force to the teeth of the developinginternally toothed gear 55 is about 20 degrees. Consequently, a normaldirection component “f” of a force transmitted from a tooth of the motorgear 52 a to a tooth of the developing internally toothed gear 55directs in a direction in which the tooth of the developing internallytoothed gear 55 separates away from the tooth of the motor gear 52 a.Accordingly, the developing internally toothed gear 55 is pushed to adirection indicated by arrow F in FIG. 17B, and therefore a contactpressure applied to a region M that is located opposite to the meshingportion K where the motor gear 52 a and the developing internallytoothed gear 55 are meshed with each other increases on the slideportion SP of the developing drive pin 55 a 2 sliding on the pininserting hole 550 a. At this time, if the grease retainer 155 a 2 islocated on the region M that is opposite to a meshing side where themotor gear 52 a and the developing internally toothed gear 55 are meshedwith each other, it is likely that the end of the grease retainer 155 a2 in the circumferential direction cuts or scratches the innercircumferential surface of the pin inserting hole 550 a.

By contrast, as illustrated in FIGS. 17A and 17B, the grease retainer155 a 2 is provided to the side on which the motor gear 52 a of thedeveloping motor 52 and the developing internally toothed gear 55 aremeshed with each other. This structure can prevent the innercircumferential surface of the pin inserting hole 550 a from hittinghard against the end of the grease retainer 155 a 2 in a circumferentialdirection. By so doing, the inner circumferential surface of the pininserting hole 550 a can be prevented from being cut by the end of thegrease retainer 155 a 2 in the circumferential direction.

Further, the developing drive pin 55 a includes a grease retainer, i.e.,the grease retainer 155 a. However, the structure applied to thisdisclosure is not limited thereto. For example, a structure in which agrease retainer is provided to the inner circumferential surface of thepin inserting hole 550 a can be applied to this disclosure.

The configurations according to the above-described embodiment areexamples. The present invention can achieve the following aspectseffectively.

Aspect 1.

In Aspect 1, a drive transmitter (for example, the drive device 50)includes an internally toothed gear (for example, the developinginternally toothed gear 55), a first support shaft (such as thedeveloping drive pin 55 a), a drive source (for example, the developingmotor 52), a rotary body (for example, the developing roller 12 a), anda grease retainer (for example, the grease retaining groove 155 a andthe grease retainers 155 a 1 and 155 a 2). The drive transmittertransmits a driving force applied by the drive source to the rotary bodyvia the internally toothed gear. The internally toothed gear is formedof resin and is rotatably supported by the first support shaft withoutusing a bearing. The grease retainer retains grease in a portion on thefirst support shaft facing the internally toothed gear and/or a portionon the internally toothed gear facing the first support shaft.

According to Aspect 1, when compared to an internally toothed gear thatis formed of metal, the internally toothed gear that is formed of resincan enhance a lighter weight, lower noise, and lower friction of thedrive transmitter. Further, by rotatably supporting the internallytoothed gear without attaching the bearing to the first support shaft,the number of parts can be reduced, and therefore an increase in cost ofan image forming apparatus having the drive transmitter can beprevented. Further, when compared to a case in which the first supportshaft is fixed to the internally toothed gear unrotatably and is fixedto a frame of the image forming apparatus, the internally toothed gearthat is rotatably supported by the first support shaft can rotatepreferably.

In addition, the drive device includes the grease retainer that retainsgrease in the portion on the first support shaft facing the internallytoothed gear and/or the portion on the internally toothed gear facingthe first support shaft. By so doing, the grease that is retained in thegrease retainer is supplied to a slide portion between the internallytoothed gear and the first support shaft, thereby reducing thefrictional force generated between the internally toothed gear and thefirst support shaft.

Accordingly, abnormal sound that is generated when the internallytoothed gear slides with the first support shaft can be restrained.Further, abrasion of the internally toothed gear and the first supportshaft can be reduced.

Aspect 2.

In Aspect 1, the internally toothed gear is formed of resin.

Accordingly, the internally toothed gear can reduce the weight, noise,and friction compared with a metallic gear.

Aspect 3.

In Aspect 1, the grease retainer includes multiple grease retainers.

Accordingly, the multiple grease retainers can supply grease to theslide portion SP between the internally toothed gear such as thedeveloping internally toothed gear 55 and the first support shaft suchas the developing drive pin 55 a.

Aspect 4.

In any of Aspect 1 through Aspect 3, the grease retainer is disposedadjacent to the slide portion where the internally toothed gear such asthe developing internally toothed gear 55 slides on the first supportshaft such as the developing drive pin 55 a.

Accordingly, as described in the examples above, the grease that isretained in the grease retainer can be supplied to the slide portionpreferably.

Aspect 5.

In any of Aspect 1 through Aspect 4, the grease retainer is a groovethat extends in a circumferential direction of the first support shaft.

Accordingly, the grease can be retained in the groove that is cut andextends in the circumferential direction of the first support shaft.

Aspect 6.

In any of Aspect 1 through Aspect 4, the grease retainer is a groovethat is cut and extends in an axial direction of the first supportshaft.

Accordingly, the grease can be retained in the groove that is cut andextends in the axial direction of the first support shaft. Further, whenthe first support shaft is made of resin, the grease retainer can beformed in an easy mold structure.

Aspect 7.

In Aspect 6, the drive transmitter further includes an externallytoothed gear (for example, the motor gear 52 a) to mesh with theinternally toothed gear (for example, the developing internally toothedgear 55) at their meshing portion and the grease retainer is disposed ona side of the meshing portion in an axial direction of the internallytoothed gear.

Accordingly, as described in the examples above with reference to FIGS.17A and 17B, the slide portion of the developing internally toothed gear55 facing the first support shaft can be prevented from abrasion at theend of the first support shaft in the circumferential direction of thegroove that is cut in the axial direction of the first support shaft,the portion on the developing internally toothed gear 55 facing thefirst support shaft.

Aspect 8.

In any of Aspect 1 through Aspect 7, the drive device further includes ahousing (for example, the resin housing 61) and a reinforcing member(for example, the reinforcement plate 90). The housing accommodates atleast one drive transmitting member (for example, the developing drivengear 56, the developing idler gear 57, and the like in theabove-described examples) in a recess thereof. The at least one drivetransmitting member transmits the driving force to the internallytoothed gear (for example, the developing internally toothed gear 55)and to the rotary body (for example, the developing roller 12 a) via theinternally toothed gear. The reinforcing member reinforces the housingand is bridged across the recess and fixed to the housing.

Accordingly, as described in the examples above, rigidity of the housingsuch as the resin housing 61 can be increased and deformation of thehousing can be restrained.

Aspect 9.

In Aspect 8, the reinforcing member such as the reinforcement plate 90includes a second support shaft (for example, the developing supportshaft 91) of the drive transmitting member to rotatably support thedrive transmitting member (for example, the developing idler gear 57).The reinforcing member has three or more fixing portions at which thereinforcing member is fixed to the housing (for example, the resinhousing 61). The second support shaft of the drive transmitting memberis provided in a position of the center of gravity of a polygon that isformed by connecting fixed portions of the reinforcing member.

Accordingly, as described in the examples above with reference to FIG.8B, a force applied to the support shaft of the drive transmittingmember (such as the developing support shaft 91) can be dispersedequally to multiple fixed portions of the reinforcing member, andtherefore torsion of the reinforcement plate 90 can be prevented.

Aspect 10.

An image forming apparatus includes an image bearer and the drivetransmitter according to any one of the Aspect 1 through Aspect 9.

Accordingly, the drive transmitter can enhance a light-weight, lessnoise device, and retain an increase in cost of the image formingapparatus.

The above-described embodiments are illustrative and do not limit thisdisclosure. Thus, numerous additional modifications and variations arepossible in light of the above teachings. For example, elements at leastone of features of different illustrative and exemplary embodimentsherein may be combined with each other at least one of substituted foreach other within the scope of this disclosure and appended claims.Further, features of components of the embodiments, such as the number,the position, and the shape are not limited the embodiments and thus maybe preferably set. It is therefore to be understood that within thescope of the appended claims, the disclosure of this disclosure may bepracticed otherwise than as specifically described herein.

What is claimed is:
 1. A drive transmitter comprising: an internallytoothed gear; a first support shaft to rotatably support the internallytoothed gear without using a bearing; a drive source to apply a drivingforce to the internally toothed gear; a rotary body to which the drivingforce is transmitted via the internally toothed gear; and a greaseretainer disposed on the first support shaft and to retain grease on atleast one of a portion of the first support shaft facing the internallytoothed gear and a portion of the internally toothed gear facing thefirst support shaft.
 2. The drive transmitter according to claim 1,wherein the internally toothed gear is formed of resin.
 3. The drivetransmitter according to claim 1, wherein the grease retainer includesmultiple grease retainers.
 4. The drive transmitter according to claim1, wherein the grease retainer is disposed adjacent to a slide portionwhere the internally toothed gear slides on the first support shaft. 5.The drive transmitter according to claim 1, wherein the grease retaineris a groove that extends in a circumferential direction of the firstsupport shaft.
 6. The drive transmitter according to claim 1, whereinthe grease retainer is a groove that extends in an axial direction ofthe first support shaft.
 7. The drive transmitter according to claim 6,further comprises an externally toothed gear to mesh with the internallytoothed gear at a meshing portion, wherein the grease retainer isdisposed on a side of the meshing portion in an axial direction of theinternally toothed gear.
 8. The drive transmitter according to claim 1,further comprising a housing to accommodate at least one drivetransmitting member in a recess thereof, the at least one drivetransmitting member transmitting the driving force to the internallytoothed gear and to the rotary body via the internally toothed gear; anda reinforcing member to reinforce the housing, the reinforcing memberbridged across the recess and fixed to the housing.
 9. The drivetransmitter according to claim 8, wherein the reinforcing memberincludes a second support shaft to rotatably support the at least onedrive transmitting member, wherein the reinforcing member has three ormore fixing portions at which the reinforcing member is fixed to thehousing, wherein the second support shaft is provided in a position ofthe center of gravity of a polygon that is formed by connecting fixedportions of the reinforcing member.
 10. An image forming apparatuscomprising the drive transmitter according to claim 1.